如何为 2 个 Mongodb 集合创建对象？

问题描述 投票：0回答：1

我目前正在做一个关于笔记应用的项目。在此之前，我只了解有关在 mongodb 中处理一个集合的知识。但在这个应用程序中，我尝试创建用户可以添加注释，将该注释添加到首选类别。在此过程中，用户可以选择首选类别。（一般，待办事项）..而且用户也可以创建自己的新类别。当用户创建新类别时，它会将其保存在数据库中，并显示已创建的类别（存储在数据库中）。

我创建了路线和开发数据库。一切工作正常。注释已创建。

//服务器.js


//other mongo db connections
app.use('/note', NoteRoutes)
app.use('/category', CategoryRoutes)

//NoteRoute.js

const express = require('express');
const router = express.Router();

const { getAllNoteData, getOneNoteData, addNewNote, updateNote, deleteNote } = require('../controller/noteController.js');




//routes for get all Note Data
router.get('/', getAllNoteData)

//routes for get specific Data
router.get('/:id', getOneNoteData)

//routes for add new note
router.post('/', addNewNote)

//update the exsist note
router.put('/:id', updateNote)

//delete the exsist note
router.delete('/:id', deleteNote)



//export rounter
module.exports = router;

//categoryRoute.js

const express = require('express');
const router = express.Router();

const { getCategory, createCategory } = require('../controller/categoryController.js');

//create new category
router.post('/category', createCategory)

//get all categories
router.get('/category', getCategory)

//export rounter
module.exports = router;

//noteController.js

//imported required modules
const mongoose = require('mongoose')
const Note = require("../models/notemodels")
const Category = require("../models/category")

//get all notes from db
const getAllNoteData = async(req, res) => {
    try {
        //all data assign to notes variable and sort by created date 
        const notes = await Note.find({}).sort({ createdAt: -1 })
            //return success response and pass data and number of notes using JSON format
        return res.status(200).json({
            count: notes.length,
            data: notes
        })
    } catch (error) {
        //error handling
        return res.status(500).json({ message: error.message });
    }
}


//get specific note based on id
const getOneNoteData = async(req, res) => {

    const { id } = req.params;
    try {
        //find the note by id and assign it into notes variable if requested data exsist
        const notes = await Note.findById({ _id: id })

        //if no data found then send not found status else pass success status
        if (!notes) {
            return res.status(400).json({ message: "No user found" });
        } else {
            return res.status(200).json(notes);
        }
    } catch (error) {
        //error handling
        return res.status(500).json({ message: error.message });
    }
}


//add new note
const addNewNote = async(req, res) => {
    try {

        const { title, content, category } = req.body;

        if (!title || !content) {
            return res.status(400).send({ message: "Please fill out all input fields" })
        }

        let categoryObj = await Category.findOne({ name: category });
        if (!categoryObj) {
            categoryObj = new Category({ name: category });
            await categoryObj.save();
        }

        const newNote = {
            title: req.body.title,
            content: req.body.content,
            category: categoryObj._id
        }

        const note = await Note.create(newNote)
        return res.status(200).send({ data: note, message: "New Note added successfully" })


    } catch (error) {
        return res.status(500).json({ message: error.message });
    }
}


//update exsist note
const updateNote = async(req, res) => {
    try {
        if (!req.body.title || !req.body.content) {
            return res.status(400).send("Complete all the empty spaces")
        }

        const { id } = req.params;

        const note = await Note.findByIdAndUpdate(id, req.body);

        if (!note) {
            return res.send("No such note found!").status(400)
        } else {
            return res.send("Update Completed Successfully!").status(400)
        }
    } catch (error) {
        return res.status(500).json({ message: error.message });
    }
}

const deleteNote = async(req, res) => {
    try {
        const { id } = req.params;
        const delNote = await Note.findByIdAndDelete(id);

        if (!delNote) {
            return res.status(400).send("No Note Found with this ID");
        } else {
            return res.status(200).send("Note Deleted Successfully")
        }


    } catch (error) {
        return res.status(500).json({ message: error.message })
    }
}

//export the functions
module.exports = { getAllNoteData, getOneNoteData, addNewNote, updateNote, deleteNote }

//类别controller.js

const mongoose = require('mongoose')
const Category = require("../models/category")


const getCategory = async(req, res) => {
    try {
        const categories = await Category.find({}).sort({ createdAt: -1 });
        return res.status(200).json(categories);
    } catch (error) {
        console.error('Error fetching categories:', error);
        console.error('Error details:', error.message); // Log error message
        return res.status(500).send({ message: 'Internal Server Error' });
    }
};

//create new category
const createCategory = async(req, res) => {
    try {
        const { name } = req.body;
        let category = await Category.findOne({ name });

        if (!category) {
            category = new Category({ name });
            await category.save();
        } else {
            return res.status(400).json({ message: 'Category already exists' });
        }
        res.status(201).json(category);
    } catch (error) {
        res.status(500).json({ message: 'Server Error' });
    }
}

module.exports = { getCategory, createCategory };

在这里，当我创建注释对象时，它创建得很好并像这样显示

 {
            "_id": "65fc8105c24e467d7397f3b4",
            "title": "Make coffie",
            "content": "use today to it",
            "color": "white",
            "category": "65fc7dcc97c1e426998de3f7",   //category object
            "createdAt": "2024-03-21T18:48:37.866Z",
            "updatedAt": "2024-03-21T18:48:37.866Z",
            "__v": 0
        }

它还创建了对象 id。这意味着它创建的某个地方。

但是当我尝试查看类别时，它显示了这个

http://localhost:3000/category


<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="utf-8">
    <title>Error</title>
</head>

<body>
    <pre>Cannot GET /category</pre>
</body>

</html>

但是当我添加这个时它会显示这个

http://localhost:3000/note/category


{
    "message": "Cast to ObjectId failed for value \"{ _id: 'category' }\" (type Object) at path \"_id\" for model \"Note\""
}

有人可以帮我学习这个吗？

reactjs node.js mongodb express mongoose
1个回答
0
投票

当您在此处安装第二个路由器时：

app.use('/category', CategoryRoutes)


CategoryRoutes
隐式内的所有路线均以
/category
开头。

所以这些路线的前缀是 

/category
:

router.post('/category', createCategory);
// Translates to http://localhost:3000/category/category

router.get('/category', getCategory)
// Translates to http://localhost:3000/category/category

您需要将它们更改为：

//create new category
router.post('/', createCategory)
// Translates to http://localhost:3000/category

//get all categories
router.get('/', getCategory)
// Translates to http://localhost:3000/category

这解释了为什么您会收到 

Cannot GET /category
，因为您的路由器中不存在该路由。

在第二个示例中，当您发出 

GET
请求时：

http://localhost:3000/note/category

Express 将请求发送至此处：

app.use('/note', NoteRoutes)

然后这里：

//routes for get specific Data
router.get('/:id', getOneNoteData)

它假定单词 

category
是 
:id
参数，并尝试将单词 
category
转换为 
ObjectId
函数中的 
getOneNoteData
，但显然不能，因为 
category
不是可转换值。

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